Technical Abstract:
Plant foods play a critical role in providing dietary iron to humans and other animals. Much of the world's human population subsists on diets that are predominantly vegetarian, while for those who eat limited to excessive amounts of animal food products, most of these foods come from livestock who are also dependent on plant sources for the majority of their dietary iron needs. Unfortunately, for humans and various animals, the concentrations of iron in the plant food supply, in conjunction with iron's limited bioavailability, can lead to iron deficiencies when these foods are consumed in common portion sizes. Thus, researchers have been interested in enhancing (i.e., biofortifying) iron concentrations in staple food crops, and/or in manipulating the food matrix to increase iron bioavailability. Current efforts to alter iron composition or bioavailability in foods, or at least to understand how this could be accomplished, include quantitative genetics approaches, functional analyses with targeted mutants or transgenic plants, fertilizer strategies, and the use of cell culture models, to name a few. Efforts are underway to manipulate staple grain and root crops, but possibilities exist to alter vegetable crops as well. In this talk, we will review the basic nutritional requirements and acquisition mechanisms pertaining to dietary iron in humans and animals. We will discuss some of the predominant plant food sources, what they can offer, and what they need to be providing to meet minimal dietary needs. We will dissect what we have learned from various QTL and gene discovery studies, as these pertain to increased plant iron concentrations, and we will assess how this knowledge must be developed to achieve future improvements in the food supply. We will introduce several recent approaches that are capitalizing on state-of-the-art methods to generate new information on the molecular components influencing iron composition in plant foods. We will review a few recent studies that have attempted to manipulate plant iron levels. We will also discuss in vitro cell culture methods that are being used to understand the genetic basis underlying plant iron bioavailability. In summary, it is hoped that this talk will provide the listener with a broad overview of the status and importance of plant iron in animal and human nutrition and a sense of where this field is heading in the coming years.